Pipe position locator

ABSTRACT

At least one sensor is mounted for monitoring the vertical position of an elevator relative to selected features on a pipe string. Mounting for a variety of sensor types is provided. Optional mounting arrangement permits the sensors to be situated close to a pipe free to move laterally, excess lateral movement of the pipe to move the mounting with reduced shock to the sensors.

[0001] This invention pertains to means for locating pipecharacteristics relative to pipe string gripping and lifting means suchas elevators on drilling and servicing rigs. More specifically in termsof the immediate need but not in a limiting sense, the apparatus detectsa change in pipe characteristics and produces a signal for use of thehuman or a signal usable directly by rig equipment when the diameter ofthe pipe string changes. Pipe characteristics changes can indicatefeatures such as the end of pipe or the location of collars and areas onthe pipe that are safe for elevator gripping.

RELATED ART

[0002] The present invention is expected to supplement the apparatus ofU.S. Pat. Nos. 4,67,312; 5,791,410, and 5,909,768

BACKGROUND

[0003] It is well known that workers on oil field drilling and servicingrigs are operating in a dangerous environment. The development andavailability of higher technology makes it increasingly easy to replacepersonnel in particularly dangerous and unpleasant activities. Manymachines can do the usual manual function of personnel. People, however,are natural sensors of considerable scope and that function is notreadily available in machines.

[0004] On manually operated rigs, people are usually the sensors wherepipe positioning is concerned. Hand signals have been well developed andserve the communication function well when exercised by experiencedpersonnel. When rigs are mechanized, the people are usually still therebut have more power at hand to carry out their purpose. When the rig isautomated, people are usually replaced. The human sensor function hasbeen removed, and it usually has to be replaced.

[0005] When pipe is being assembled into a pipe string in a well by amanually operated or mechanized rig, a stabber is needed. A stabber is aman who works about forty feet above the derrick floor in about theepicenter of engine fumes, glaring lights, and a noise level rarelyexperienced elsewhere. He usually aligns the top of a pipe section withthe well centerline so that threads will run, without binding, duringthe section adding process. Another of his functions is to signal thedriller who is in control of the draw works that the elevator has theright elevation to safely engage the upper end of the pipe string forsafe lifting.

[0006] When it is needed to dispense with the stabber, he will not bethere to affirm that the pipe is suitably positioned for closing theelevator on a pipe location for safely supporting the pipe string load.A pipe position sensor is needed such that the driller, or automaticdriller, will know the pipe position is safe for closing the elevatorsand opening the spider.

[0007] The sensor will preferably ride the elevator, or relatedstructure, to simplify indication of information relative to theelevator position.

[0008] At times, the area above the pipe string, along its extendedcenterline, is occupied and that space cannot always be used for a pipeend sensor. A connector coupling, or a substitute, is usually somewhatlarger in diameter than the pipe being connected. Sensing the connector,or other preselected feature, can provide the needed information forselecting the elevator position relative to the pipe, before clampingthe elevator on the pipe string. Clamping the elevator on the pipestring is essential before releasing the slips on the spider.

[0009] To sense diameter change when pipe can move laterally, aplurality of some commonly available distance sensors can be used,distributed around the periphery of the elevator central opening.Collectively, they can indicate the diameter, or change in sensedcharacteristics, of pipe string components that will often be displacedfrom the general centerline of the gripping apparatus. In principle ofoperation, there are several concepts that are candidates. Examplesinclude at least those listed below. 1. Sound ranging, much like sonar.2. Magnetic proximity detection. 3. Light, several beam formats arepossible. 4. Air flow interference. 5. Mechanical contact. 6. Capacitive

[0010] Some of the principles of operation listed above suggest three ormore sensors distributed about the periphery of the pipe to be measured.Capacitive, air interference, and a form of magnetic detection may besubject to simple peripheral wrap of one sensor. Because of the lateralrange of movement of the pipe, until gripped, the sensors have to besome distance from the pipe outer surface, or accept movement by thelateral excursions of the pipe. All sensors considered usable aresubject to mounting on structure that can move the sensors,collectively, in lateral directions with little sacrifice of ruggedness.

[0011] A sensor with a single peripheral wrap can be described, forinstance, as a short tubular capacitor with an axis of symmetrycoincident with an extended pipe centerline. An equivalent magneticsensor would be a single coil, of one or more conductor turns,distributed much like the capacitor. An air impact equivalent would be aperipheral slit nozzle projecting air radially inward along the entireperiphery.

[0012] The preference for first utilization is the mechanical feelersensor. The mechanical sensor can directly operate elevator slipactuator inhibitor apparatus without adding a special communication orsensor power assistance to the elevator. Also, a mechanical contactmechanism is easy to arrange for calibration, and certification can besimple.

SUMMARY OF INVENTION

[0013] A mounting and handling system is provided for using a variety ofinterchangeable sensors to sense the vertical position of pipe stringcharacteristics relative to an elevator. The sensors are adjustable fordiameters sensed and for vertical distance above the elevator slips. Thesensors all serve much the same function but different sensors arecompatible with different environments or circumstance of use. Thepreferred system will work with different sensors and require a minimumof change in the overall system to accommodate the sensor changes.

[0014] An object of the invention is to provide means that enableoperating personnel to assure that pipe string elevators are in aposition, relative to the pipe to be gripped, to activate pipe gripingdies to grip the pipe string in a stable location, for safety and otherreasons. Diameter differences between pipe string components usuallyhave a known vertical relationship to safe gripping areas on the pipe.In some cases, there are no pipe diameter changes suitably locatedrelative to acceptable pipe gripping areas on the pipe string. In suchcases, there are usually other detectable features, such a knurledsurfaces, peripheral grooves and other features that can be sensed bysome physical feature sensor. Combinations of features may be present tooffer assurance that what is sensed is not an unexpected anomaly.Features and combinations of features may be referred to herein ascharacteristics. That is anticipated by and is within the scope of theclaims.

[0015] To accept the lateral movement of the pipe within the elevator,before the slips are closed, the sensor means is optionally mounted on atransition, or adapter, plate that can move laterally on top of theelevator a selected amount in all lateral directions. That reduces themaximum distance between the pipe and the diameter, or feature, sensormeans. The sensor means may be a single sensor surrounding the pipe, ora plurality of independent sensors distributed around the pipe.

[0016] A measuring system called a light curtain is reasonablyindependent of distance to object problems and is a separate categoryneeding no transition plate.

[0017] Signal conditioner modules are available to receive sensor outputsignals that do not directly serve the intended purpose and they processthe signal, usually by media conversion or computational processes.Multiple sensors distributed peripherally around a pipe string willrarely produce a directly usable signal from each sensor. A geometricequation usually has to be solved and a usable resultant produced. Airvalves that receive signals in the form of mechanical movement andproduce changes in air flow, still to be used as a signal elsewhere, isa form of signal conditioner. If the rig is automated, the signal willbe adapted to satisfy the input needed for the particular apparatusinvolved. Signal distribution is adaptable to circumstances and mayinclude, singly or collectively, display for human observation ormachine usable data. Additionally, the signal may be used directly bythe elevator to inhibit, or compel, selected actions.

[0018] The vertical position of the pipe string can be derived fromfeatures of the pipe string, such as changes in diameter as the pipemoves relative to the elevator. Such features of the pipe are known andcan be related to a suitable pipe gripping area. The signal that thediameter of the pipe has changed can be used to immediately close theelevator slips if the sensor is situated a sufficient distance above theslips. If the pipe is cylindrical below the connector sensed, the slipscan normally be closed as soon as the diameter change is sensed. In casethe pipe has a long taper below the connector, operating personneleither position the sensor a sufficient distance above the slip to clearthe taper, or the operating personnel move the elevator a selecteddistance after the sensed diameter change for the slips to be situatedbelow the tapered surface.

[0019] Sensors utilizing light are usable for diameter determination. Inone form, known as a thin profile light curtain, a light beam isprojected across a selected area at selected lateral intervals. Thetraversing beam elements can be very close together if necessary. Thenumber of beams occluded define the lateral dimension of the occludingobject.

BRIEF DESCRIPTION OF DRAWINGS

[0020]FIG. 1 is a side elevation of a typical elevator suspended by theusual bails from the traveling block.

[0021]FIG. 2 is a top view of the elevator of FIG. 1, without bails.

[0022]FIG. 3 is a top view of a light curtain sensor mounted on anelevator

[0023]FIG. 4 is a side view of the assembly of FIG. 3.

[0024]FIG. 5 is a side view of the elevator of FIG. 1 with no bails buthaving a transition plate to carry the sensors.

[0025]FIG. 6 is similar to FIG. 5 but fitted with a single peripheralmagnetic sensor.

[0026]FIG. 7 is similar to FIG. 5 but is fitted with an alternate sensorarrangement.

[0027]FIG. 8 is similar to FIG. 7 but is fitted with a plurality (oneshown) of mechanical feeler sensors mounted on a transition plate thatis spring centered.

[0028]FIG. 9 is similar to FIG. 8 but rigged to amplify the signal fromeach transducer to increase the magnitude of the mechanical outputsignal.

[0029]FIG. 10 is a side view of one sensor and mounting means shown inFIG. 9.

[0030]FIG. 11 is a side view, mostly in cut-away, of an air curtaindetector system.

[0031]FIG. 12 is a side view, simplified, of a stacked sensorarrangement.

DETAILED DESCRIPTION OF DRAWINGS

[0032]FIGS. 1 and 2 show a common drilling rig slip-type elevator 1 witha pipe P extending through the central opening and terminating withcollar 2. Sensors 4 respond to changes in detectable characteristics ofpipe P. The pipe can move some distance in any lateral direction beforethe slips are set. The sensors 4 read at some distance from the pipe butif the reading distance is greater than a certain amount, transitionplate 3 can be used to carry the sensors and move a small amount in anylateral direction if hit by the pipe.

[0033] The movable plate 3, best seen in FIG. 5 has vertically confiningshoulder screws in laterally loose holes. Caption 16 notes the assembly.The sensors can be mounted closer to the pipe yet allow the pipe to movea greater lateral distance before damaging sensors.

[0034]FIGS. 3 and 4 show a multiple beam light projector and receiverarrangement known as a light curtain. It is usable as a remote sensor tomeasure features by the number of light beams occluded. Housing 10projects the plural beams of light 12 across the area to be partlyoccluded by pipe, and housing 11 receives the surviving light beams andproduces a consequent signal output usable by the operating personnel orancillary apparatus. The signal processing gear is normally situated inone of the housings. Light curtains are purchasable items.

[0035]FIG. 5 shows a general purpose sensor mounting arrangement to beconsidered in view of FIG. 1. Sensor 4 a is symbolic of magnetic,capacitive, sound, light, or contact sensors, or a combination of morethan one type sensor.

[0036] The sensor detects the change in diameter, or other detectablecharacteristics, when the pipe is moving through the elevator. Thechange will, cause the sensor to send a signal along communication link6 (FIG. 1) to read out near the operating personnel. If an automaticdriller is in charge, unit 7 (FIG. 1) will be the input receiver for thedevice involved. Link 6 may include any form of communication and mayextend to a number of end user entities.

[0037] Ordinarily, the elevator slips could be closed as soon as thecollar 2 a is sensed if the sensors are in the positions, relative tothe slips, as shown.

[0038]FIG. 6 shows a single sensor 4 c distributed peripherally aroundthe pipe. The transition plate is shown but may not be needed in allcases. Sensor 6 can be a magnetic coil, capacitive plate, or air flowinterference. Controlling processors are not shown, can be mounted onthe elevator or elsewhere, and are established in the art.

[0039]FIG. 7 is similar to FIG. 5 but has mechanical contact feelersensors 4 b that are spring biased toward the pipe. Position sensorsdetect the position of all feelers and convey the information to acomputer cell that may be in the sensors, mounted on the transitionplate, or located elsewhere. The computer will indicate the diameter ofthe pipe or just the change in diameter, indicating in this figure thata collar is sensed. FIG. 8 shows a related version in more detail.

[0040]FIG. 8 is identical to FIG. 7 except for a spring bias arrangement14 that tend to center modified plate 3 a but allows the springs 15 onthe sensor feelers to collectively influence the position of thetransition plate, to reduce shock imposed by plate travel limits.

[0041]FIGS. 9 and 10 are a more detailed description of the mechanicalsensor equipped system of FIGS. 7 and 8. Elevator 1 is fitted withtransition plate 3 (already described) carrying sensor assemblies 4 d.The mechanical contact sensors move radially from the pipe centerline. Awire line, or filament, 20 circumnavigates the pulleys 32 carried by thesensor slides 33. Spring 34 urges slide 33 toward the pipe and urgesslideway 35 away from the pipe being sensed (not shown). The collectivebias applied to the slideways centralizes plate 11 relative to the pipebeing sensed. The system will work without plate 3 but the slideways mayneed to be longer to extend the travel of the slides. The standard(stanchion) 31 connects wheel 30 and the slide 33.

[0042] The filament 20 responds to the radial movement of the sensorscollectively and moves the input to sensor 21 an amount approximating2.8 times the sensed change in diameter of the related pipe stringcomponent. The filament is a simple way to process the input signalsfrom the sensors collectively. Any equivalent system may be used. Sensor21 is a pneumatic valve which controls air flow related to slip closurein the elevator. In converting movement of said filament to changes influid flow resistance, the valve serves as a form of signal conditioner.The air circuitry controllable is now operational in the elevatorsrelated to the referenced US patents.

[0043]FIG. 11 shows what is often called a thin profile air curtainsensor 4 e. The annular chamber 42 is contained in housing 41 and issupplied an air stream 44 through supply tube 43. Slit nozzle 40 isperipherally distributed around the central opening in elevator 1. Airprojected radially inward from the slit nozzle 40 causes a back pressurein chamber 42 that is influenced by any object encountered by the movingair stream. With a given air flow 44 the pressure in chamber 42 is aspecific amount if no object is in the elevator central opening. Withany object in the central opening, the chamber pressure is higher. It ishigher an amount that is proportional to the objects effective diameter.The chamber pressure can be read directly by a driller from a gaugeextended some distance from the elevator, or the pressure can beconverted to other signal forms for use by people or machines.

[0044]FIG. 12 shows a stacked sensor arrangement. No elevator is shown.Sensor 10 of FIG. 3 is situated above sensor 4 e of FIG. 11. If sensor10 senses the diameter of the collar and sensor 4 e senses the diameterof the pipe, the different signals from the sensors will indicate thecollar-to-pipe transition is between the two sensors. This arrangementshould work as well with the single point sensors without distributingthem around the object to be sensed, even of the pipe can move laterallysome limited amount.

[0045] From the foregoing, it will be seen that this invention is onewell adapted to attain all of the ends and objects hereinabove setforth, together with other advantages which are obvious and which areinherent to the invention.

[0046] It will be understood that certain features and sub-combinationsare of utility and may be employed without reference to other featuresand sub-combinations. This is contemplated by and is within the scope ofthe claims.

[0047] As many possible embodiments may be made of the locator of thisinvention without departing from the scope thereof, it is to beunderstood that all matter herein set forth or shown in the accompanyingdrawings is to be interpreted as illustrative and not in a limitingsense.

The invention having been described, we claim:
 1. A pipe string featurelocator for detecting the vertical position of a pipe string suspendedin a well relative to the rig elevator, the locator comprising: a) adrilling rig elevator to function as a carrier for pipe feature sensorsand related mounting means; and b) at least one said pipe featuresensors mounted on said elevator and arranged to sense selectedcharacteristics of pipe extending through the elevator and to produce anoutput signal indicative of the presence of selected pipecharacteristics.
 2. The pipe string feature locator according to claim 1wherein said output signal is a change in the resistance to the flow offluid through a valve actuated in response to changes in the pipefeature changes.
 3. The pipe string feature locator according to claim 1wherein said output is an electrical signal, at least part, in a digitalformat.
 4. The pipe string feature locator according to claim 1 whereinsaid diameter sensor is part of a plurality of sensors, each of whichhas a mechanical element extending from the sensor to the surface ofpipe extending through the elevator.
 5. The pipe string feature locatoraccording to claim 4 wherein said plurality of sensors, each, contributepart of the total signal.
 6. The pipe string feature locator accordingto claim 5 wherein said sensors each carry a pulley that moves radiallyin sympathy with changes in sensed pipe diameter, a filament reevedabout all said pulleys such that the movement of the pulleys,collectively, results in a consequent proportional change in the lengthof filament needed to complete the circuit about all pulleys, saidchange in needed filament length being satisfied by movement of an inputmember of a signal conditioner which produces the output signal.
 7. Thepipe string feature locator according to claim 1 wherein said sensorprojects a stream of air toward the surface of said pipe, and detects achange in resistance to the air flow caused by changes in thecharacteristics of the pipe.
 8. The pipe string feature locatoraccording to claim 7 wherein said signal is conveyed as a pressurechange.
 9. The pipe string feature locator according to claim 1 whereinsaid sensors are mounted on a transition plate which is laterallymovable, within limits, relative to the elevator to which it isattached, by which the sensors can be mounted closer to a pipe capableof lateral movement within the elevator.
 10. The pipe string featurelocator according to claim 1 wherein said sensors emit sound to impingeupon the surface of the pipe, and respond to echo characteristic todetermine distance between reference features in the sensor and thepipe, said output signals from each sensor being processes to producesensed pipe feature related information.
 11. The pipe string featurelocator according to claim 1 wherein the function of said sensor isachieved by the arrangement of at least two sensors on differentvertical locations, by which process the sensors collectivelyaccommodate lateral movement of said pipe, both sensing the movement,and the feature change being sensed when one sensor detects pipe stringfeatures the other sensor does not detect.
 12. The pipe string featurelocator according to claim 1 wherein said sensor is a light curtaincomprising a plurality of laterally spaced light beams projectedhorizontally across space said pipe may occupy.
 13. The pipe stringfeature locator according to claim 1 wherein said sensor is a magneticfield producing and responding arrangement.
 14. The pipe string featurelocator according to claim 1 wherein said sensor is a capacitivearrangement arranged to respond to the proximity of pipe and sensor tochange electrical characteristics of the sensor to be interpreted interms of changes in pipe diameter.
 15. A pipe string feature locator fordetecting when a selected characteristic on a pipe string suspended in awell has a preseleced vertical relationship to the rig elevator, thelocator comprising: a) sensor means to detect at least onecharacteristic of the pipe that has a known vertical relationship to alocation on the pipe selected for gripping with elevator mounted pipegripping means and to produce an output signal when the characteristicis sensed; b) a sensor mounting arrangement that places the sensor meansthe same distance and direction from the elevator pipe gripping means asthe known distance and direction between the characteristic to be sensedand the location on the pipe selected for gripping.